fundamentalism, type of militantly conservative religious movement characterized by the advocacy of strict conformity to sacred texts. Once used exclusively to refer to American Protestants who insisted on the inerrancy of the Bible, the term fundamentalism was applied more broadly beginning in the late 20th century to a wide variety of religious movements. Indeed, in the broad sense of the term, many of the major religions of the world may be said to have fundamentalist movements. For a discussion of fundamentalism in American Protestantism, seefundamentalism, Christian.